Post object error in RestKit

Question

I'm posting object with below code

Models

@interface Event : NSManagedObject
@property (nonatomic, retain) NSString * eventID;
@property (nonatomic, retain) NSString * title;
@property (nonatomic, retain) Calendar *calendar; // many-to-one

@interface Calendar : NSManagedObject
@property (nonatomic, retain) NSString * calendarID;
@property (nonatomic, retain) NSSet *events; // one-to-many

RKRequestDescriptor

RKObjectMapping *calendarRequestMapping = [RKObjectMapping requestMapping];
[calendarRequestMapping addAttributeMappingsFromDictionary:@{
                                                             @"calendarID":@"calendar"}];
RKObjectMapping *postRequestMapping = [RKObjectMapping requestMapping];
[postRequestMapping addAttributeMappingsFromArray:@[ @"title"]];
[postRequestMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"calendar" toKeyPath:@"calendar" withMapping:calendarRequestMapping]];

RKRequestDescriptor * eventRequestDescriptor = [RKRequestDescriptor requestDescriptorWithMapping:postRequestMapping objectClass:[Event class] rootKeyPath:nil method:RKRequestMethodPOST];
[objectManager addRequestDescriptor:eventRequestDescriptor];

POST

[[RKObjectManager sharedManager] postObject:event path:@"/events/" parameters:nil success:nil failure:nil];

According to the server log, What I posted is

{u'calendar[calendar]': [u'3b60a22c-d46e-46ca-b978-ec81a8b47fcb'], u'title': [u'xxxxx']}

What I expect is

{u'calendar': [u'3b60a22c-d46e-46ca-b978-ec81a8b47fcb'], u'title': [u'xxxxx']}

I have tried

[calendarRequestMapping addAttributeMappingsFromDictionary:@{
                                                             @"calendarID":nil}];

Or

[postRequestMapping addPropertyMapping:[RKRelationshipMapping relationshipMappingFromKeyPath:@"calendar" toKeyPath:nil withMapping:calendarRequestMapping]];

Both of them will throw an exception.

Answer 1

I just fixed this issue with below mapping

RKObjectMapping *eventRequestMapping = [RKObjectMapping requestMapping];
[eventRequestMapping addAttributeMappingsFromDictionary:@{
                                                         @"title":@"title",
                                                         @"calendar.calendarID":@"calendar"}];